shivakumarmakka wrote:
Logic of GMAC is:
Before Event X: A was LESS than B.
After Event X: A equals B. OR A is larger than B.
Conclusion: X must cause A increase.
Assumption is: No factors make B decrease
I think that after the event X,A did not increase but B decreased due to predation so how can the conclusion be X must cause A increase ( although A might have increased through reproduction) At some point both A and B became equal
Can anyone please clarify!?
Dear
shivakumarmakkaI'm happy to respond.
Let's say
A = black earthworm population
B = red-brown earthworm population
Before event, A < B. Technically, A = 5B, approximately.
BUT, be careful. After event, it does not say A > B or even A = B. The exact wording is
"
The population of black earthworms is now almost equal to that of the red-brown earthworm ..."
Technically, A is still less than B: now, not five times less, but just slightly less. It's misreading the question to say that A is greater than B.
Also, notice that nowhere in the question itself does it suggest that the black worms have increased. The prompt argument doesn't even contain the word "
increase." In fact, the question is about B decreasing. The factory has blackened the woods, and presumably the black worms are now well camouflaged, but the red-brown worms are easier to spot, so the birds snack on these. We don't know whether the black worms have stayed the same or increases, but through some combination of B dropping and A staying the same or rising, A has almost caught up to B.
My friend, you have to remember that GMAT CR is as precise as mathematics. You have to look at every single word incredibly carefully. It appears you got the gist of the argument and concluded in your own mind that it was saying things different from what it actually says. Be very careful. As in any argument in the business world, the fine print matters, and many business deals that look great on the surface turn out to be nightmares when you examine the details.
Does all this make sense?
Mike
_________________
Mike McGarry
Magoosh Test PrepEducation is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)